The invention relates to an apparatus for grinding semifinished steel products, particularly but not exclusively in the form of billets, requiring material removal up to the depth of penetration of cracks near the surfaces. The apparatus includes a grinding wheel which is movable in respect of its height position relative to the semifinished product and has its axis arranged substantially parallel with the longitudinal axis of the product whilst the semifinished product is simultanenously advanced in the direction of its longitudinal axis and rotated about the latter. A stop member in the shape of a segment having approximately the same curvature as the grinding wheel relative to the grinding wheel axis controls the position of the grinding wheel relative to the surface of the semifinished product so that material is removed uniformity around the entire periphery of the semifinished product. The stop member is vertically adjustable and rests on the unabraded surface of the semifinished product at a position which is spaced beneath the point of engagement of the grinding wheel by a distance which corresponds to the penetration depth of the grinding wheel.
Such an apparatus is known from U.S. Pat. No. 2,347,639. In that case an arcuate stop member in the form of a slipper is vertically adjustable by means of a screwspindle on an arm which is secured to a support. The support engages operatively with a lever which carries the bearing of the grinding wheel. In practice a multi-link mounting assembly of this type not only leads to a very expensive construction but also to substantial transmission faults due to dimensional deviations of the individual links from their respective designed measurements and their progressive wear which is very considerable under the rough operative conditions involved in the grinding of semifinished steel products.
A similar device for grinding semifinished steel products is also known from U.S. Pat. No. 2,558,943. Here switch levers are provided on both sides of continuously advancing steel billets to be ground. These levers are encountered by the billet edges on turning and trigger the switches of switching circuits which by means of further switches for which a cam controlled by sensor fingers resting on the faces of the billets and associated with an actuating device is provided which controls the supply of compressed air to pneumatic cylinders. The latter have one part thereof mounted on the machine frame whilst their respective other parts are applied to a bearing arm of the grinding wheel and thus allows grinding pressure to be modified in relation with the given rotational position of the billet. This grinding pressure control is so arranged that in the vicinity of the edges the application pressure is reduced so that corresponding to the longer dwelling time in this region some equalisation is obtained. However, in so far as the preselected relation of grinding pressure to angular position does not correspond to the actual functional conditions, the intended equalisation is only partly achieved. In particular, the specific grinding pressure depends very largely on the material composition. Added to this it must be remembered that even if all the other material influences are known, local strength variations in the semifinished products cannot be detected and that these may well be the cause for inadequate equalisation of material abrasion.
It is further known, according to French Pat. No. 66 400, in the grinding of billets to reduce the edge pressure of the grinding wheel by means of an hydraulic control system which in turn is subject to the influence of an hydraulic adjusting member which is charged by a roller sitting on a template which revolves with the billet. The actual billet measurements however are not detected in this case. Moreover, the grinding-pressure control is subject to the above described influential factors.